There’s probably no provider, paid or otherwise that you can be guaranteed to be safe with because they all rely on automated systems that can make mistakes. I would say you have more chance for active support if you go with a paid service like Proton though.

Apart from that, redundancy makes sense - don’t rely on a single email provider/service but have several independent email identities with your mail synced across them. This goes for associated data too - the worst part of having your account locked is losing access to your cloud-stored contacts, files, etc.